C&DH
Philip Luers
NASA/GSFC Code 561
August 16-17, 2005
NASA’s Goddard Space Flight Center
18b - 1
Requirements Flow-Document Tree
LRO Requirements
Document
431-RQMT-00011
CRaTER EICD
431-ICD-000094
Diviner EICD
431-ICD-000095
LRO Mission Assurance
Requirements
RLEP MAR 430-RQMT-000006
MAR
LRO ELV Mission
Specification
RLEP-LRO-P40
MRD
LRO ELECTRICAL SPEC
431-SPEC-00008
LRO Mechanical Environments
and Verification Requirements
431-RQMT-000012
LAMP EICD
431-ICD-000096
LAMP DICD
431-ICD-000106
LRO Radiation Requirements
431-RQMT-000045
LRO PSE ICD
431-ICD-000018
LEND EICD
4301-ICD-000097
THERMAL SYSTEM SPEC
431-SPEC-000091
LOLA EICD
431-ICD-000098
COMMUNICATION SYSTEM
REQUIREMENTS
431-REQT-000137
LROC EICD
431-ICD-000099
LROC DICD
431-ICD-000109
LRO Flight
Software Requirements
431-REQT-000139
C&DH Requirements
431-RQMT-000168
SpaceWire SPEC
431-SPEC-000103
CDH
FSW
1553B Bus Spec
431-SPEC-000102
LVPC REQs
Section 6
SBC REQs
Chassis REQs
Section 14
HK/IO REQs
NASA’s Goddard
Space
Section
7 Flight Center
Section 8
Thermal REQs
Section 9
SSR REQs
Section 10
KaComm REQs
Section 11
S-Band REQs
Section 12
Backplane REQs
Section 13 18b
-2
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements to all C&DH Sub-Assemblies
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-033
1.3.3.3
Electrical Interfaces:
C&DH shall comply with the LRO Electrical System SPEC 431-SPEC000008.
Each Board has the electrical
breakdown documented in
Section 3 of its requirements.
Power Consumption and Inrush
Current are documented.
MRD-034
1.3.3.4
Thermal Interfaces:
C&DH shall comply with the LRO Thermal System Specifications 431SPEC-000091
Box meets these requirements.
Section 5 of each board details
additional thermal methods taken
(i.e. heat sinks) to meet LRO
Thermal requirements.
MRD-068
1.4.12
EEE Parts Radiation:
C&DH shall meet the requirements of the LRO Radiation Requirements
Doc 431-RQMT-00045
Section 1.1 of each board details
additional radiation requirements
and mitigation where necessary.
NASA’s Goddard Space Flight Center
18b - 3
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements to Single Board Computer (SBC)
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-086
3.5.4.1
FSW and ACS SW Processing Storage:
The SBC shall provide TBD MIPS processing platform for FSW and
ACS SW.
This value is based on a 5
second average CPU utilization
calculation as required in the
GFSC-STD-1000 pg 60 and
table 3.07-1.
MRD-108
3.5.4.2
Boot Code Storage:
The SBC shall provide minimum 64KB of non-reprogrammable (in-flight)
non-volatile storage of SUROM boot code.
To mitigate the potential
EEPROM Radiation and soft-bit
issues, PROM is used for
SUROM boot code.
MRD-108
3.5.4.3
Application Code Storage:
The SBC shall provide minimum 4MB of non-reprogrammable (in-flight)
non-volatile storage for EEPROM application code.
To mitigate the potential
EEPROM Rad and soft-bit
issues, the 4MB EEPROMs are
used to store 2 identical flight
application code images with a
hardware switchover option.
MRD-108
3.5.4.4
Executable Code Storage:
The SBC shall provide minimum 20MB of volatile storage for SRAM
executable code storage.
Storage for applications code,
data tables, data.
MRD-109
3.5.1.1.2
1553B Bus Controller:
The SBC shall operate as Bus Controller (BC) for 1553B as a default.
Designed to operate as either BC
or RT on 1553B.
NASA’s Goddard Space Flight Center
18b - 4
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Data Volume
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-118
3.5.4.5
SBC SRAM Data Storage:
The SBC shall provide a minimum of 20 MB memory for storage of
housekeeping data whenever the SSR is off.
Whenever the Solid State
Recorder is turned off, all
spacecraft and housekeeping
data shall be recorded in the
SBC. SBC shall have additional
SRAM for data storage.
MRD-037
3.5.7.1
SSR Data Storage:
Normal Operations: The SSR shall provide at least 400Gbits End Of Life
(EOL) of memory capacity for incoming data files for science data and
housekeeping data collection.
SSR Storage requirement:
(Based on 4 ground station
passes back to back, each 45
minutes long with the time
between last and first pass is
~1044 minutes). SSR needs to
store 6.4 Mbps (6.4x10e6)
average data rate (includes all
instruments and S/C
engineering) for at least 1044
minutes. Gives approximately
391 Gbits (3.91x10e11)
(assuming max LROC data, 16
NAC pairs per orbit). Also based
on downlink rate of 125 Mbps
(1.25x10e8).
NASA’s Goddard Space Flight Center
18b - 5
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Networks
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-035
3.5.1.1
Low Speed Bus (LSB) 1553B:
C&DH shall utilize a MIL-STD-1553B network per Electrical System
Spec 431-SPEC-00008 to interconnect subsystems and instruments for
telemetry, commanding, and low speed instrument data.
Industry standard interface
simplifies interfaces, improves
flexibility and supports future
growth.
MRD-109
3.5.1.1.2
1553B Bus Controller:
The SBC shall operate as Bus Controller (BC) as a default.
MRD Level 2 requirement.
MRD-035
3.5.1.1.3
LSB Scheduling:
The C&DH shall initiate predictable transactions on the LSB according
to a pre-planned schedule; accurate to +/-5ms and synchronized to the
1 Hz pulse.
Ensures reliability of data
transfer.
MRD-036,
MRD-038
3.5.1.2
High Speed Bus (HSB) SpaceWire:
C&DH shall utilize a SpaceWire network per LRO SpaceWire SPEC
430-SPEC-000103 to interconnect subsystems and instruments for
telemetry, commanding, and high rate data, maximum rate of 125 Mbps
(125x10^6).
Industry standard interface
simplifies interfaces, improves
flexibility and supports future
growth.
Downlink schedule and data
volume drive the data rate.
NASA’s Goddard Space Flight Center
18b - 6
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Telemetry
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-112
3.5.6.1
C&DH Comm Telemetry Encoding:
C&DH Comm System shall provide telemetry encoding options i.e.
Reed Solomon (RS), Bi-Phase-L, NRZ-L or NRZ-M.
All are supported by ground
stations.
MRD-110
3.5.6.2
C&DH CFDP:
C&DH Comm system shall support CFDP.
Meets FSW and Comm
requirements per LRO 431REQT-000137.
MRD-028,
MRD-113
3.5.6.3
C&DH Comm Ground Test:
C&DH Comm system shall provide a hardline interface for ground test
through the spacecraft umbilical.
Method for integration and test
without using RF components.
MRD-110,
MRD-123
3.5.6.5.2
S-Band Downlink Telemetry:
C&DH S-Band shall support CCSDS downlink telemetry at a maximum
rate of 2.186 Mbps (2.186x10^6).
Science data and housekeeping
data source. Meets Comm
requirements per LRO 431REQT-000137
MRD-110,
MRD-124
3.5.6.4.1
Ka-Comm Downlink Telemetry:
C&DH Ka-Comm shall support CCSDS downlink telemetry at a
maximum rate of 125 Mbps (125x10^6).
Science data and housekeeping
data source including TLM
encoding. Meets Comm
requirements per LRO 431REQT-000137
NASA’s Goddard Space Flight Center
18b - 7
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Commands
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-119,
MRD-122
3.5.6.5.1
C&DH S-Band Telecommand:
C&DH shall support CCSDS telecommands at a maximum rate of 4
Kbps (4x10^3).
Consistent with requirements of
flight software and
communications. C&DH can
support up to 16Kbps (1.6x10e4).
MRD-111
3.5.6.5.1.1
C&DH Hardware Decoding:
C&DH shall perform hardware decoding of critical commands. Generate
5 RS422 outputs.
Method for recovery from
anomalous conditions. Ongoing
safe-mode and recovery
scenario studies. C&DH can
support up to 8 outputs.
NASA’s Goddard Space Flight Center
18b - 8
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Timing
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-042
3.5.2.2,
1.3.4.1.1
Barker Time:
C&DH shall record the time of receipt of last ground telecommand.
To ensure reliability of
communication link to the ground
station.
MRD-068
3.5.2.1
Watchdogs and External Resets:
The C&DH shall provide and control a watch dog timer.
To prevent a software continuous
loop failure.
MRD-042
1.3.4.1.2
Other Errors:
The timing error due to other error sources shall be less than 1 ms. [The
sources of error (clock, stability, accuracy of distribution, latency of
timetick, transmit time)]
Must be less than 3 ms
knowledge requirement.
MRD-043
1.3.4.2.1
Oscillator Drift:
The onboard oscillator shall not drift by more than 100 ms in 24 hours
over the operational temperature range.
Maintains ability to execute
stored commands within 100 ms
of desired UTC time with an
accuracy of 1ms.
NASA’s Goddard Space Flight Center
18b - 9
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Timing
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD-157
1.3.4.2.2
Oscillator Stability:
The oscillator stability shall meet the timing requirements in Section
1.2.1.1 in the presence of the measurement errors described in Section
1.2.1.2.
Selected an oscillator with a
frequency stability of 10 ppb.
MRD-043
1.3.4.2.3
Time Correction Accuracy:
The C&DH shall provide a mechanism to correct Orbiter time to within
100 ms of UTC time.
Ensures maintenance of
accuracy.
MRD-114
1.3.4.3
MET Counter:
The C&DH shall provide a Mission Elapsed Timer (MET) that cannot be
adjusted.
Standard design reduces the
design complexity and meets the
requirements.
MRD-042
1.3.4.3.1
MET Resolution:
The MET counter shall have a resolution of 15 microseconds.
For accurate commanding.
C&DH shall utilize a 16-bit subsecond counter .
MRD-043
1.3.4.3.2
MET Rollover:
The MET counter shall be capable of operating for 5 years without
rollover.
No discontinuities wanted. The
use of a 28-bit second counter
supports rollover not occurring
for 8.5 years.
MRD-043
1.3.4.4
Pulse Per Second:
The C&DH shall provide a 1 Hz pulse as required by the instruments.
For timing and synchronization of
commands.
NASA’s Goddard Space Flight Center
18b - 10
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Flow Down Key
Requirements for Instrument Interfaces
Level 2 Req.
Level 3: Requirements
Paragraph
MRD-117
1.3.4.5 , 3.5.1.2
2.3.13
2.3.5
Concept/Compliance
Requirement
RS422 Serial LSB
C&DH shall provide an asynchronous 38400 baud RS422 Serial LSB
for telemetry and commanding to the LAMP instrument.
All telecommands and time messages shall be transmitted to LAMP
via an asynchronous 38400 baud RS422 Serial LSB
LAMP/Pluto heritage.
Meets LAMP DICD 431-ICD000106.
LAMP shall transmit science data using LVDS compliant chips.
MRD-116
MRD-117
1.3.4.5, 2.3.1.3
Time Message RS422 Serial LSB:
C&DH shall provide the LAMP instrument a time message via RS422 serial
LSB.
Meets LAMP DICD 431-ICD000106.
MRD-035,
MRD-116
1.3.4.5, 2.1.2.1,
2.2.2.1, 2.4.2.1,
2.5.2.1
Time message 1553B:
Meets Instrument ICD’s.
MRD-036,
MRD-116
1.3.4.5,
2.6.2.1
SpaceWire Time Code Message:
C&DH shall provide the LROC instrument a Time Code Message every 1 Hz
via SpaceWire.
NASA’s Goddard Space Flight Center
C&DH shall provide the following instruments a time message via 1553B:
CRaTER, Diviner, LEND, and LOLA.
Meets LROC DICD 431-ICD0000109.
18b - 11
LRO C&DH Architecture Block Diagram
L
E
N
D
SUBSYSTEMS
(ACS, PSE,
PRO/DEP)
NAC1 NAC2 WAC
D
i
v
i
n
e
r
C
R
A
T
E
R
L
O
L
A
MiniRF
LROC
SpaceWire
FPGA
32 Mbps
1553B
5 Heater out
Unsw.+28V
SpaceWire
FPGA
8 to 32Mbps
(Max.)
Hi-Rate
Tlm
125Mbps
(Max.)
38.4Kbps Serial IF
(UART)
1Mbps
S-Xpndr
HGA
Ka-Xmtr
Low-Rate
Tlm 2Mbps Max
& Command 4Kbps
HGA
Gimbals
2.186 Mbps Max. (HK Downlink)
Sw. +28V (Heater)
Sw. +28V (Ka-Comm)
2.186 Mbps Max. (LAMP
Tlm)
125 Mbps (Science Downlink)
50 Mbps Max. (Tlm)
I/O
Sw. +28V (SSR)
L
A
M
P
Unsw. +28V
UnSw. +28V (S-Comm)
1PPS
1553
Summit
LVPC
( A)
BAE
1553
Summit SpaceWire
ASIC
Thermal
Card
RAD750
SBC
BAE
SpaceWire
ASIC
SSR
SpaceWire
FPGA
HK/IO
SpaceWire
FPGA
KaComm
SpaceWire
FPGA
SComm
(B)
+28V Power
+/-15V, +5V, +3.3V (A)
SpaceWire (HSB)
+3.3V (B)
Backplane (Power & POR)
C&DH
NASA’s Goddard Space Flight Center
1553B (LSB)
18b - 12
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Verification
• Analysis
▪ FPGA/ASIC (Worst-case Timing Simulation, Test Benches)
▪ Board-level (Test Benches, Throughput Performance, Signal Integrity)
• Testing
▪ Component
• Radiation (+1.5V Linear Regulator, ACTEL FPGA AX series, Micron SDRAM
dies)
▪ Subsystem
• Board-level (BB, ETU & FLT)
• Box-level (ETU & FLT)
▪ Environments
• EMI/EMC, Thermal Vacuum, Vibration (FLT)
▪ System I&T
• FLATSAT: Subsystems Electrical Interface Testing (ETU)
• Spacecraft (FLT)
• Orbiter: EMI/EMC, Thermal Vacuum, Vibration, Acoustic (FLT)
NASA’s Goddard Space Flight Center
18b - 13
Lunar Reconnaissance Orbiter (LRO)
C&DH System Level 2 Summary
•
•
•
•
•
C&DH Level 2 Requirements are defined, and are traceable to LRO
requirements.
▪ C&DH architecture meets these requirements.
All C&DH requirements have been captured in a requirements document.
▪ Requirements and technical resources have been allocated to
assemblies.
C&DH Requirements are in the process of submission to CM for release.
Key Interface Requirements are defined.
▪ Have initiated ICD-Level interface definition, some TBD’s pending.
Key Trade Studies and Analyses have been completed (Data Volume,
1553B, SpaceWire)
C&DH is ready to continue Preliminary Design.
NASA’s Goddard Space Flight Center
18b - 14